Combination regular and test connector for automatic telephone systems



July 18, 1950 H. CREECH COMBINATION REGULAR AND TEST CONNECTOR FOR AUTOMATIC TELEPHONE SYSTEMS Filed June 26. 1947 INVENTOR. HASELL E. GREEGH ATTO RNEY Patented July 18 1950 COMBINATION REGULAR AND TEST CON- NECTOR FOR AUTOMATIC TELEPHONE SYSTEMS Hasell E. Creech, Orangeburg, S; 0., assignor .to Automatic Electric Laboratories, Inc., Chicago, lilL, a corporation of Delaware Application June 26, 1947, Serial No. 757,185

1 4 Claims.

This invention relates to testing arrangements in general, particularly to testing arrangements for use in small automatic telephone systems and is concerned primarily with improved apparatus for extending a connection from testing equipment to a subscribers line terminating in an automatictelephone exchange.

In large automatic telephone systems it is usual practice to install a test connector switch for each group of connectors, the test connector being accessible only to authorized persons in the telephone exchange. However, in small exchanges, say 400 lines or less, the cost of installing separate test connectors is not Warranted, therefore a feature of this invention is a simple and inexpensive means of converting one regular connector in each connector group so that it will not only be accessible to all subscribers for regular telephone calls, but also be accessible to authorized personnel of the telephone exchange for use in testing the subscriber lines in that connector group.

Essentially the functions of a test connector is to allow direct access to the line in question without any appendages on the line within the exchange, irrespective as to the line being in an idle or busy condition, so that various test instruments may be connected thereto for the purpose of measuring the line constants, causing ringing tests of the subscribers signalling device, dial speed and percent make contact tests of the calling device and checks for open or shorted loop and ground faults.

A feature of this invention is the inexpensive and simple means whereby, upon the addition of a relay and a switchboard jack to one of the existing connector switches within a connector group, the connector is converted for use both as a regular connector as well as a test connector.

The invention is shown diagrammatically on the associated drawing and for purposes of this specification a connector switch of the well known Strowger type is illustrated. This connector switch, which has been converted for use as a regular connector as Well as a test connector, is arranged for use on ten party lines using harmonic ringing, whereby one-half of the subscriber station signalling devices are connected between one side of the line to ground and the other half connected between the other side of the line and ground, therefore full selective ringing for the stations is accomplished in the well known manner.

Upon reading the 1 following specification it will readily be seen that this conversion ofa 2 regular connector into a combination connector is not necessarily limited to the one type of connector as shown, but may be used with other types well known in the art.

Referring now to the drawing, as previously mentioneda standard connector switch for ten party selective harmonic signalling is shown, and a standard ten point switch I90, having two banks of contacts, commonly known in the art as a Minor Switch, is the means whereby the selective signallingis controlled.

The test relay I and the switchboard jack mu together with the associated wiring are the additions to the standard connector switch which form the bodyof this invention.

When a subscriber wishes to call another subscriber, the calling subscribers talking circuit will be extended, upon the removal of his handset, to a free selectorv switch, not shown, and upon dialing the hundreds line digit of the call number the calling line will be connected to the conductors l0 and H in a manner well known in the art. The dialing of the tens line digit of the call number will cause the connector switch to adwance its wipers vertically to the desired level and dialing of the units line digit will-advance the wipers horizontally to the terminals of the called line. A last and final digit of the call number corresponding to the station signalling number is dialed and thereby steps the Minor Switch Hill to the desired position corresponding to the generator frequency and the side of the line over which the signalling current is to be sent out.

It has been assumed, for purposes of simplif ying this specification, that the testrelay I80 is mounted on the connector switch base, whereas the switchboard jack Hill, the busy lamp I06, the calling device I and the release key K are con-. nected to the connector switch by means of outside connections, vsay cable 30, and are mounted at a convenientplace in the exchange. There is a switchboard jack and a busy lamp associated with each connector switch converted for test purposes and the calling device m5 and release key K are common to all of said jacks. It follows that if the automatic exchange in question is equipped for, say 400 subscriber lines, there would be four combination regular and test connector switches, one for each group of one hundred subscriber lines, and four switch board jack and lamp combinations. Access toa combination connector for testpurposes isvia the telephone type plug I01 which is insertedinto the switchboard jack 100. The tip and ring of the plug being connected to leads to which the necessary testing equipment, represented by the rectangle I08, terminates as needed.

The operation of the connector switch, shown in Figure 1, as a regular connector, will now be described, tracing a call from one subscriber to another subscriber within the automatic telephone exchange. When the connector switch is seized by a calling subscriber through the medium of preceding switches, the line relay IIO operates over the closed loop by way of the talking conductors I and II and contacts H6 and H1. Relay IIO, upon operating, at make contacts III energizes the hold relay I20. Relay I20, upon operating, at contacts I25 places holding ground on the control conductor I2 by way of contacts I98 and I85 to maintain the preceding switches and also energizes the lower winding of the vertical transfer relay I35, at contacts I2I opens a point in the release circuit, at contacts I22 prepares a portion of theimpulsing circuit, at contacts I23 prepares a locking circuit for relays I40 and I10 and at contacts I24 prepares the operating circuits for relays I10 and I60. Relay I35, upon operating, at make contacts I36 further prepares the impulsing circuit to the vertical magnet 50 and in multiple, a circuit to its own upper winding. When the tens digit of the line number is dialed by the calling subscriber, line relay IIO releases and reoperates in the well known manner in accordance with the number of impulses of the dialed digit, causing the operation of the vertical magnet 50 to step the wipers I3, I4 and I of the switch opposite the corresponding level of bank contacts. Upon the first operation of the vertical magnet 50 the vertical oiT-normal springs V. O. N. operate and at contacts I99 closes a point in the switch release circuit and at contacts I98 open the energizing circuit to the lower winding of relay I35. Relay I35, however, is of the slow-to-release type and will remain operated throughout the series of dialed impulses by means of its upper winding which is energized each time the line relay IIO restores in response to the dialed number. At the end of this series of impulses, the vertical transfer relay I35 restores, opening at contacts I36 the circuit to its upper winding and the vertical magnet 50 and prepares a multiple circuit to the rotary magnet 52 and the rotary transfer relay I30.

Responsive to the next digit dialed by the calling subscriber, the rotary magnet 52 is operated under the control of the line relay H0 in the usual manner and rotates the switch wipers I3, 14 and I5 into engagement with the bank contacts terminating the line conductors of the called number. Relay I30 operates in multiple with the rotary magnet 52, remaining operated during impulsing due to its 'slow to-release characteristics and at contacts I3I opens a point in the busy tone circuit and at contacts I32 closes an operating circuit to relay I60. Relay I60 operates by way of ground at contacts I16, make contacts I 32 to negative battery through its upper winding. Relay I60 at contacts I6I and I62 closes a point in the ringing circuit, at contacts I63 opens a point in the operating circuit of the switching relay I 10, at contacts I64 prepares a circuit to its lower winding and at contacts I65 connects ground from contacts I24, through contacts I45, I84, I11 to the lower winding of relay I55. Relay I55, however will not operate, it being shunted by ground from contacts I'1'6 by way of contacts I32 and I59.

At the end of the series of impulses relay I30 restores and at contacts I32 opens the operating circuit to relay I60, also removing the shunt from relay I55. Relay I55 now operates by way of ground at contacts I24, contacts I65, I45, I84 and 11, lower winding relay I55, upper winding relay I60 to negative battery. Relay I60 therefore remains operated. Relay I55, upon operating, at contacts I56 transfers the impulsing circuit from the rotary magnet 52 to the motor magnet I9I of the Minor Switch I90, at contacts I51 closes a multiple path of the impulsing circuit, at contacts I58 closes a point in the circuit for the busy relay I90, and at contacts I59 prepares a circuit to its upper winding and to the lower winding of relay I60.

The last or ringing digit of the call number is now dialed and the motor magnet I9I is operated under the control of the line relay IIO in the usual manner and rotates the wipers of the minor switch banks A and B to the terminals corresponding to the dialed digit, the off-normal springs I 93 and I94 closing on the first step of the switch and remaining closed until the wipers are restored to their normal position. Relay I30 reoperates in multiple with the motor magnet NH and remains operated for the duration of the series of impulses of the last digit and at contacts I32 connects ground from contacts I16 to the upper winding of relay I55 and to the lower winding of relay I60. Relay I60 is a differential type relay, its windings being in opposition to each other, therefore upon the energization of its lower winding the relay restores, opening at contacts IBI and I62 the ringing circuit, at contacts I63 closing the busy test circuit, at contacts I64 opening the circuit to its lower winding and at contacts I65 opening the holding circuit to its upper winding. Relay I55 is held operated during the series of impulses of the last digit by its upper winding, therefore a circuit is closed to the busy relay I50.

If the called line is busy, relay I50 operates by way of ground on the control wiper I5, contacts I83, I63 and I58 to negative battery. Upon operating, relay I50 at contacts I5I closes a point in the busy tone circuit, at contacts I52 opens a point in the impulsing circuit, which however, is being maintained by relay I55 at contacts I51, and at contacts I53 prepares its own locking circuit.

At the end of the series of impulses of the last dialed digit, the rotary transfer relay I30 restores, placing at contacts I3I, busy-tone through the condenser C5 and contacts I5I, to the negative talking conductor, which in the usual manner will indicate to the calling subscriber that the called line is in use. Relay I30, upon restoring, also at contacts I32 opens the holding circuit to the upper winding of relay I55. Relay I55, upon restoring, at contacts I51 opens the impulsing circuit so that no further impulses, if accidentally transmitted, will afiect the switch and at contacts I58 closes the locking circuit to the busy relay I50.

If however, the called line is idle, negative battery from the cut-off relay, not shown, of the called lines line circuit will be encountered by the wiper I5 therefore, the busy relay .559 will not operate. Relay I55 now being in its deenergized position, as mentioned above has closed at contacts I58 an operating circuit for the switching relay I 10. Relay I10 operates by way of ground at contacts 424, contacts I53, lower winding of relay I10, off normal springs I93, contacts I58, I63 and I83, wiper I to negative battery through the called line cutofi relay. RelayI now closes at contacts I a holding circuit to its upper winding, at contacts I13 close the circuit to the generator start lead, at contacts Ill and I12 prepares the ringing circuit, at contacts I14 opens the impulsing circuit, at contacts I16 places ground on the control wiper I5 to maintain the called line line equipment, and the called line busy, at contacts I11 prepares an operating circuit to the upper winding of relay I60 and at contacts I18 connects the pick-up lead to th upper winding of relay I60.

Ground is momentarily placed on the pick-up lead at the start of a ringing cycle, which operation is well known in the art, and therefore relay I60, upon operating by way of its upper winding, at contacts I65 transfers its operating circuit from the pick-up lead to ground at contacts I24, at contacts I53 opens the initial energizing circuit of relay I10, and at contacts I6I and I62 closes the ringing circuit to the called line.

The called line is now signalled in the well known manner from ground connected interrupted generator lead 3, assuming that the last digit dialed was 3, through the thirdcontact' of the bank A of the Minor Switch, its wiper, contacts IBI, MI and Ill, wiper I3, out over the negative side of the called line, through the called station signalling device and condenser to ground. Ring back tone is impressed on the calling line through condensers CI, 02, C3 and C4 in the well known manner. If however, the last digit dialed was 8, the Minor Switch wipers would, therefore be on the eighth terminals and the generator lead 3 would now be connectedto the positive side of the called line by way of wiper I4.

When the called party answers a directcurrent loop is closed in the well known manner and the ring cut-off relay I40 operates, by way of ground on the generator lead 3, over the negative line, through the called subscribers station, back over the positive line to the upper winding of the ring cut-off'relay I40 to negative battery. Relay I40, upon operating, at contacts I42 closes a holding circuit to its lower winding, at contacts IM and I43 disconnects the ringing circuit from the talking conductors and completes the talking path between the calling and called subscribers, at contacts I44 opens the generator start circuit and prepares another holding circuit for its lower winding and relay I10,and at contacts I45 opens the holding circuit to relay I60. Relay I00 restores and further opens the ringing circuit.

Upon the closure of the talking path by relay I40 the back-bridge relay 5 operates over the called subscribers loop and at contacts H6 and Ill reverses, the calling line connections in the well known manner to give supervision, at contacts IIS opens another point in the release circuit and at contacts II9 closes another point in the holding circuit for relays I40 and I10.

Talking battery is now supplied to the calling subscriber by the line relay I I0 and to the called subscriber by the back-bridge relay 5' and conversation may now commence.

When the calling and called subscribers have completed their conversation they will replace their handsets which opens their respective talking loops and the connector switch is restored to normal. In case the calling subscriber restores his handset before the called subscriber, relay IIO will restore to normal, which in turn restores relay I20, Relay I20 upon restoring, at

contacts I25 removes ground from the control lead I2 which allows'the previous switches oper# ated by the calling subscriber to restore to normal. Nothing else happens at thi time as the back-bridge relay H5 is held operated by the called subscribers closed loop and relays I40 and I10 are held operated by the ground connected through contacts II9.

However, when the called subscriber replaces his handset, relay II5 restore and at contacts II9 opens the holding circuit for relays I40 and I10, which in turn restore and at contacts II8 completes the release circuit.

This release circuit may be traced from ground at contacts II8, through contacts I2I, Minor Switch off-normal springs I94 to the release magnet I92 of the Minor Switch. The release magnet I92, upon operating, allows the wipers of the Minor Switch to restore to their normal position at which point the off-normal springs I93 and I94 are opened, thereby opening the circuit to the release magnet I92. The release ground at contacts H8 also can be traced through con tacts I2 I through the vertical off-normal springs I99 to the release magnet 5| oi the connector switch. The release magnet 5I, upon operating, allows the switch wipers I3, I4, and I5 to restore to normal, the vertical oif-normal springs I98 nd I99 closing and opening respectively when the switch shaft reaches its normal restored position.

Use as a test connector If the connector switch is to be used for testing a subscribers line, the exchange attendant inserts the plug I01, to which is connected the necessary test equipment, I08, into the switchboard jack I00 which actuates the auxiliary contact springs IOI, I02 and I03. Upon the insertion of the plug I01 into the jack I00 the test relay I operates by way of ground at contacts I I8, contacts I2I and I82, winding relay I00 to negative battery at contacts I93. Relay I00, upon operating, at make-before-break contacts I93 places ground on the control wiper I5 and opens the operating circuit for the switching relay I10 and the test circuit for the busy relay I50, at contacts I8I connects the negative talking conductor I0 through contacts I02 and the key K to one of the impulse springs of the calling device I05, at

make-before-break contacts I02 closes a locking circuit for itself, at contacts I84 opens the holding circuit for relay I60 and at contacts I removes negative battery through the lower winding of relay I35 from the control conductor I2, thereby making the connector switch busy to'any preceding switch. The lamp I06, connected in multiple with the winding of the test relay I80, lights, indicating that the connector is being used for test purposes. The positive line conductor I-I is connected by way of contacts IOI to the other impulse spring of the calling device I05, therefore completing a circuit for the operation of the line relay IIO. Relay IIO operates and as explained previously prepares the switch to receive dialed impulses. The exchange attendant now dials the number of the line to be tested on the calling deawn-aces tor wipers I3, and Marc now connected, free of any appendages to the test equipment by way of the tip T and ring R springs of the jack I and the plug I0'I, so that testing of the line may be done. If a station on the line being tested is to be signalled the correct ringing frequency is connected to the tip and ring leadsin the test equipment I08 and will be extended out over the line by way of conductors 23 and 2 When testing of the line has been completed and the exchange attendant wishes to test another line immediately next to it on the same horizontal bank level, he may dial the digit one which will momentarily deenergize the line relay I I0 which in turn closes the operating circuit for the rotary transfer relay I and the rotary magnet 52 in multiple, thereby rotating the switch wipers one step. It will be noted that this digit is the same as a third digit for ring selection when the connector switch is used by a subscriber, but that the test relay I80 has, at contacts I84, opened up the circuit for the ring transfer rela I55 so that it will not operate and connect the Minor Switch I90 into the impulsing circuit. Relay I will operate each time relay I30 operates but has no efiect on the operation of the switch and will not lockup as previously described. The switch wipers may also be rotated one step by momentarily opening the key K, which is in eiiect the same as dialing one, however the key should not be held open long enough to cause the release of the hold relay I20.

When the exchange attendant wishes to test a line on a different horizontal level than that on which he has been testing, he will operate the t:

key K, which will open the circut for the line relay I-III causing it to restore and in turn restore the hold relay I20. Upon the restoration of these two relays the switch release circuit will be closed and the connector switch wipers will return to normal at which time the key K may again be closed, and upon the reoperation of the line relay H0 and the hold relay I20, the connector switch will again be in condition to receive further H dialed impulses for selecting another line to be tested. The connector switch, however, will remain busy to precedin switches as the test relay I is still operated and at contacts I has removed battery potential from the control lead I2.

Upon the removal of the plug IIl'I from the jack I00, the circuits to the line relay I I0 and the test relay I80 will be opened, the indicating lamp I06 extinguishes, and therefore the connector switch will restore to normal condition and be free to receive a call placed by a subscriber.

This completes the description of the operation of the invention and what is considered new and is desired to have protected by Letters Patent is suificiently stated in the appended claims.

What is claimed is:

1. In a telephone system, an automatic switch, two circuits having access to said switch for sei ing said switch, a first relay in said switch, means for operating said relay in case said switch is seized from either of said circuits, means for operating said switch to extend a connection, a

circuit controlled by said operated first relay for maintaining said switch operated, another relay in said switch, means including a circuit completed for operating said other relay in case said switch is seized from one of said circuits, and contacts on said first relay circuit for disabling said other relay in case said switch is seized from the other of said circuits.

2. In a telephone system, an automatic switch, two paths over which said switch may be seized and over which trains of impulses may be received for operating said switch, a magnet for operating said switch, means for operating said magnet responsive to one train of impulses received by said switch in case it is seized over either of said paths, an auxiliary switch, means for operating said auxiliary switch responsive to a subsequent train of impulses received by the first of said switches in case it is seized over one of said paths, means for disabling said auxiliary switch operating means in case said first switch is seized over the other of said paths, and said first means effective after operation of said disabling means for reoperating said magnet responsive to a subsequent train of impulses received by the first of said switches in case it is seized over the other of said paths.

3. In a telephone system, an automatic switch having incoming and outgoing conductors, a test position, a path for seizing said switch, means for connecting said test position to said incoming conductors to seize said switch over said path, another path for seizing said switch, means for preventing the connection of said test position to said incoming conductors in case said switch is seized over said other path, and means for connecting said test position to said outgoing conductors regardless of whether or not said switch is seized.

4. In a telephone system, an automatic switch, a first path for seizing said switch, a second path for seizing said switch, control apparatus operated responsive to seizure of said switch over either said first path or said second path, a relay operated in case said switch is seized over said second path, circuits completedby the operation of said relay for operating said control apparatus, means in said control apparatusfor disabling said relay in case said switch is seized over said first path, and contacts on said relay for disabling said first path to prevent seizure of said switch in case said switch is seized over said second path.

I-IASELL E. CREECI-I.

REFERENCES CITED The followingreferences are of record in the file of this patent:

UNITED STATES PATENTS Number 'Name Date 1,543,900 'Berte'ls' June 30, 1925 1,813,138 Beale July 7, 1931 1,864,553 Quass June 28, 1932 2,327,458 Relfe Aug. 24, 1943 

